Elevated convection has continued with isolated showers and brief thunderstorms due to the steep middle level lapse rates and moisture advection. Recent satellite imagery showed this focused on an apparent elevated boundary oriented SW to NE from about Ottumwa to Galena. At the surface...winds have become gusty as expected from the southwest while temperatures as of noon were well into the lower 80s. Despite the deeper mixing under partly to mostly sunny skies...dewpoints were climbing into the lower 70s over most of the area.

At noon...the cold front was roughly from west central WI SW to near kfsd. 12z models and high res convective models are in general agreement with strong to possibly severe storms holding off until very late afternoon or evening along the cold front prognosticated roughly from dbq to dsm at 00z. Deeper shear developing during this time...with high convective available potential energy likely in place will support severe storms and the Storm Prediction Center 16z update has maintained a slight risk over most of the forecast area...with enhanced touching northeast Stephenson County.

Will be updating the forecast to focus probability of precipitation close to the late afternoon frontal timing with little change to highs that will push the upper 80s to near 90.

&&

Synopsis... issued at 329 am CDT sun Aug 2 2015

An agitated altocumulus castellanus deck associated with a quick moving vorticity maximum in the steering flow was located from Escanaba Michigan to Hastings NE. Extremely isolated convection has formed in this band as it marches to the southeast at around 20 kts. At the surface...dewpoints are pooling across the area and relatively clear skies remain across the area. With the pooling moisture....temps have been slow to drop across the area. Guidance suggests an 850 mb thetae push of near 50 degrees into the area near 12z. This and the vorticity maximum will dominate our weather in the next 6 to 12 hours.

&&

Short term...(today and tonight) issued at 329 am CDT sun Aug 2 2015

Main forecast concern for the short are the chances for thunderstorms and rain today. There are two chances with the first one either ongoing at 12z or starting shortly thereafter. The other is associated with a cold front that will move through the area today and into tonight. Some of the storms later this afternoon and evening could be strong to severe.

This morning the altocumulus castellanus deck moving into the area will encounter an 850 mb thetae push. These two are forecast to be coincident across the County Warning Area near 12z. This could lead to the development of showers and thunderstorms across the area. Large scale models hint at this possibly happening...however the mesoscale nature of the forcings are difficult for the models to handle correctly. Perusing the cams...which do better with mesoscale features...it is clear that these models do suggest additional thunderstorm development this morning with the wave. At this time...these storms are not expected to be severe. A strong storm with small hail could be possible. I do not have high confidence in this occurring so decided to go with schc probability of precipitation until the altocumulus castellanus becomes better agitated. Any storms this am could leave outflow boundaries that may influence convection later.

This afternoon...guidance suggests that mixing will result in high temperatures in the 90s across the area. Soundings indicate the eml has resulted in drier air aloft. As this drier air is mixed down...the temperatures should increase and dewpoints should lower. Used mosguide for the dewpoints as they seemed to have a better handle on what was going on now and mixing the dewpoints lower this PM. As a result...heat indices will remain below criteria.

Late this afternoon a cold front will move through the area. Looking at the thunderstorm potential...there will be sufficient deep layer shear for isolated cells. With the main forcing to the north...these storms may be slower to grow upscale into a mesoscale convective system. Lapse rates in the middle levels suggest that hail will be the main threat. With the high temperatures and likely higher storm bases...damaging winds could also be possible. Low level shear and hodos are indicative of the possibility of tornadoes as well. In fact they are very favorable for possible tornadoes. However...the thermodynamic environment is not. I think the threat of tornadoes is higher with an mesoscale convective system instead of a supercell storm that may be the first Mode of development. Regardless there is a threat for severe weather from these storms.

Looking at the cams...the NAM 4km has the bulk of the storms and bowing structures across WI and east Illinois. This model probability of precipitation short lived isolated cells that struggle to grow upscale into a mesoscale convective system structures. The wrfnmm and arw are eerily similar in which a frontal mesoscale convective system comes through our area instead of to the east. Regardless these models produce storms and thus give ME higher confidence that convection will occur. Did not go higher than chance as I do not have an idea of which of the solutions will occur. Later shifts may be able to increase probability of precipitation across the area as the day progresses and a clearer solution is seen.

Monday and Monday night... northwest flow aloft will dominate early in the week as anomalously deep upper low (500 mb heights of 550-555 decameters equating to roughly 2+ Standard deviations below climatology per naefs) remains parked near Quebec. This flow pattern coupled with high pressure ridge building in will result in cooler (near normal) and drier conditions to start the week. A surface front is anticipated to stall out from the Central Plains to the Appalachians by Monday evening. Isentropic lift and weak low amplitude shortwaves will provide focus for precipitation chances near and on cool side of boundary...with the far southern County Warning Area potentially in close proximity to some of this activity.

Tuesday and Tuesday night... overall pattern not showing much change during this period with upper low slow moving through Ontario... and County Warning Area staying on cool side of stalled frontal zone from the plains through the middle-Mississippi Valley. Thus... more of the same with pleasant conditions with near to slightly below normal temperatures and comfortable humidity levels... and any rain chances mainly to our South/West in vicinity of stalled front with southern County Warning Area standing any chances for rain being in closer proximity to boundary.

Wednesday through Saturday... continued gradual drawn down on temperatures to below normal expected into late week with influx of cooler air (850 mb temperatures lowering into range of 12-16c) in wake of departing Ontario upper low. In addition...likelihood of intervals of cloudiness with series of upper level disturbances propagating through region in the semi-zonal to northwest flow to aid in keeping temperatures below normal. With surface front nearby will maintain rain chances through Thursday then trends support drying out late week into the weekend with another bout of Great Lakes ridging and influx of cooler...drier air.

Isolated...high based showers may affect the mli terminal early this afternoon. Otherwise...VFR conditions will be in place with gusty southwest winds and warm temperatures. Scattered thunderstorms are expected along a cold front dropping south into the area this evening and have focused tempo groups for this timing at Cid...dbq and mli. Confidence in timing and coverage is lower for brl...where a prob30 group was utilized. Overnight through Monday morning...light north-northwest winds are expected with mostly clear skies.